Carburetor



June l5, 1965 J. l.. szWARGuLsKl 3,l89,33l

GARBURETOR Y Filed Aug. 1e. 1963 2. sheets-sheet 2 mgwnam JESSE L .szwARGuLsKl United States Patent O 3,189,331 CAREURETR .fesse I.. Szwargulski, Florissant, Mo., assigner to ACF industries, lneorporated, New York, NX., a corporau tion of New .lersey Filed Aug. 16, 1963, Ser. No. 302,676 3 Claims. (El. Zul-oil) This application is a continuation-inpart of my cepending application Serial Number 131,175, filed August l4, 1961 now Patent No. 3,136,327.

This invention is directed to a carburetor for an internal combustion engine and particularly to the means for metering fuel from the carburetor fuel bowl.

in one type of carburetor the fuel passage from the source of fuel to the air and fuel mixing conduit of the carburetor includes a metering jet such. as a predetermined restricted orifice to meter fuel to the mixing conduit. The fuel flow through this jet is metered or controlled in accordance with the demands of the engine. The type of carburetor described utilizes a metering rod with one end having a thickness of varying amounts. This end of the rod is arranged to be adjustably moved within the re stricted orifice to provide more or less fuel, depending upon the demand of the engine. The metering rod is operated by an air motor connected to the mixing conduit of the carburetor downstream of the throttle, so that it is responsive to the pressure conditions of the intake manifold which vary during engine operation. The air motor moves the tapered end of the metering rod through the fuel metering jet to permit more or less fuel to pass through the jet in accordance with engine demands.

It is desirable in carburetors of this type to be able to assemble the parts of the air motor easily and with a minimum amount of time and number of operations. In such an operation it is also necessary to set the diaphragm of the air motor so that upon assembly the diaphragm retains sufficient slack as to be properly operable to move the metering rod.

lt is therefore an object of this invention to provide a novel carburetor structure utilizing a novel air motor for operating the metering rod.

It is another object of this invention to provide a fuel and air mixing device utilizing novel air motor structure for moving a metering rod in which the air motor is easily assemble-d with minimum operations.

It is a further object of the invention to provide a novel diaphragm operated air motor for a metering rod in which during assembly the diaphragm is properly set with sufficient slack for the desired operation.

The invention is directed to a carburetor utilizing a fuel metering rod in the fuel passage thereof in which the fuel metering jet is at the base of a fuel well, which in turn is a portion of the body casting. This well portion of the body is suspended Within the fuel bowl of the carburetor. Upon removal of the fuel bowl alone, the metering jet is immediately accessible for removal. The metering rod is arranged such that the tapered or metering end of the rod is operatively positioned within the fuel metering jet. However, the rod itself is of a dimension such that the jet need not be removed for removing and replacing the metering rod. The upper end of the metering rod is held within a resilient retainer so that the rod may be removed by grasping the lower end of the rod and pulling it out of the retainer. `A new rod can be inserted in reverse order and its upper `end will snap into the retainer to be again releasably held in operative position. The retainer forms a means for connecting the metering rod to an air motor which is a diaphragm movably operated by a spring in one direction and by atmospheric pressure in the other direction in response to manifold vacuum. The motor housing is shaped so that upon assembly the motor spring Syldglii Patented .finie 15, 1965 ICC presses the diaphragm against the housing wall to provide the sufficient loop or slack in the diaphragm for proper operation. The air motor parts are designed that they can be easily assembled with a minimum of tooling and assembly operations.

FIGURE 1 is a plan view of a carburetor embodying the novel features of this invention.

FIGURE 2 is substantially a longitudinal sectional view of the carburetor of FIGURE 1, which is shown mounted on an engine manifold and with an air filter partially in section.

FIGURE 3 is a partial sectional View of the carburetor of FIGURE 1 and along section lines 33 of FIGURE 1.

FIGURE 4 is an enlarged sectional View of a portion of FIGURE 3 illustrating the features of the invention.

FIGURE 5 is a sectional View of a retainer utilized in the carburetor and in accordance with the invention.

FIGURE 6 is a partial view of one end of a metering rod in accordance with the invention.

FIGURE 7 is a plan view from below the retainer of FIGURE 5.

The carburetor shown in FIGURES l and 2 consists essentially of a single casting 10, which is formed with a fuel and air mixture conduit 12 and .a fuel bowl cover portion 14 from which is integrally formed a depending accelerating pump cylinder 16 and accelerating fuel passage 18 and a fuel well structure 20. As shown, the mixture conduit l2 is arranged and aligned vertically during operation and is connected by a flange 13 to the intake manifold M of an internal combustion engine E. In the lower part of the conduit 12 there is rotatably mounted a throttle valve 22 fixed to a throttle shaft 24 journaled in appropriately aligned apertures of the body casting 1t). In the upper portion of the fuel-air mixture conduit 12 there is similarly mounted for rotational movement an unbalanced choke valve 26 fixed to a choke valve shaft 2S, which is also journaled in aligned apertures through the body casting 10. To the top of the mixture conduit 112 is connected an air filter `29, partially shown in section in FIGURE 2. Between the upper and lower portions of the mixture conduit 12 is formed a venturi or air flow restricting surface portion Sil. A small booster venturi 32 is formed integrally with the body casting 10 and has an inner venturi surface 34 eoaxially aligned with the mixture conduit 12 and the primary vent-uri surface 3d.

A fuel bowl 36 which may be of a plastic is fixed beneath the fuel bowl cover 1d and is held with its rim tightly against a gasket 33 fitted between the rim of the fuel bowl 36 and matching portions of the fuel bowl cover 14 by screws 37 threaded into anged portions of the fuel bowl cover 1.4i. A iioat structure 4i) is pivotally mounted from pin 42 journaled in a depending portion of fuel bowl cover 14. A lever arm of the float lever 43 fixed to fioat di) abuts the lower end of a needle valve d4 having an upper tapered end extending into a valve seat 46 of the inlet 47 to the fuel bowl 36. A fitting may be threaded into inlet 47 to connect the carburetor to `a fuel line 48. Fuel is forced under pressure by a pump f5@ from a fuel tank 52, both schematically shown, through the fuel line d3 and linto the carburetor inlet 47. With the fuel level in bowl 36 low, the float d0 is lower and lever arm 43 allows Valve 44 to be pressed by fuel pressure and gravity to an open position. Fuel flows into the bowl 36 and when it reaches a predetermined level, the float lever 43 presses upwardly against the needle valve 44 to close the inlet to the fuel bowl.

The lower end of the fuel Well Ztl 4is closed by a threaded fitting 56 having a central orifice 69 (FIGURE 4) therethrough which is carefully formed to provide a metering jet `for the flow of fuel rfrom the fuel bowl 36 to the mixture conduit 12. .A `screw driver slot 57 is provided in the `bottom of fitting 56 to provide for its removal. The upper end of the fuel well 29 intercepts a cross vfuel passage 58 directed downwardly into the secondary venturi structure 3-2. A nozzle fitting 69 is presstted into the end of passage 58 and has one end thereof extending into the center of the secondary venturi surface 34. Press-fitted within the well Ztl is a fuel emulsion tube 62 having apertures 63 therethrough along its length, as shown in FIGURE 4.

A metering pin 66 is suspended within the fuel well 26. Pin e6 has an end 63 formed with varying thicknesses. The formed end 68 is positioned within the main fuel jet -or-ifice 69 for operation in response to engine requirements. Flow of fuel through the i ain jet 56 is controlled by the metering rod 66 and in accordance with that portion of the formed end 68, which is positioned within the jet 56, as described below.

In accordance with a feature of the invention, the metering rod 66 is supported from a retainer 79 in which the upper end of rod 66 is frictionally engaged. The retainer 79 has somewhat the shape of 4an eyelet, as shown in cross-section in FIGURE 5, and is bifurcated at its lower end at 72, as shown in FIGURES and 7. The retainer is made of a `resilient plastic material such as Delrin and has an axial passage therethrough with an opening at its lower end which is smaller than the diameter of the upper end of the metering rod 66. Because of the resilient nature of retainer 70 the rod 66 may be pressed into the open end 72 and a sharp rib 74 .around the inner periphery ofthe 4opening 7-2 is caused to snap into a circumferential Igroove 76 formed in the upper end of the metering rod 66.

In accordance with another feature of this invention, a light .spring 78 is positioned within a bore 77 between a shoulderportion 79 of the body casting 10 and the upper fianged end of the retainer 70. Spring 7S is o-f a strength to merely overcome the weight of retainer 7i) and the rod 66 and to thus always bias the upper surface of retainer 70 against a diaphragm 8i) which is sealed in -an air tight manner at its peripheral edge between a shoulder 8d of the body casting and a fitting S2 pressed into a matching bore 84 of the 'body casting. Diaphragm 89 extends across a cavity 36 which is formed from a depression in the bottom of bore 84 and fitting 82. On the upper side of diaphragm Sti, opposite to the ,side against which the retainer 70 is biased, is positioned a second or separate retainer structure 88 identical in construction to retainer 79. A spring 90 is positioned between the top of a central bore 91 of fitting 82 and the lower flanged surface of the retainer 88 to bias the retainer 38 and diaphragm 8i? in a downward position, as shown in FIGURES 2 and f 4, `for example, bores 91 and '77 are coaxially aligned but off to one side of the axis of the cylindrical well 20. This suspends metering rod 66 to one side of the Well axis and biases the rod end 68 eccentrically within jet orifice 69 against the side of the jet fitting 56. This provides a consistent flow of fuel through orifice 69 for any position of the metering rod 66.

The bore 931 is connected by a cross passage 92 to an annular passage 93 formed in the peripheral surface of the fitting 32. As shown in FIGURE 3, in particular, a passage 94 is formed through the body casting liti to the fiange portion 13 of the carburetor and opens at 95 into the mixing conduit and manifold M below or downstream of the throttle 212. `In this manner, passage 94 connects the portion of cavity 86 above the diaphragm Si) to the manifold pressure of the engine The various parts of the metering rod and air motor assemblies are specifically designed to minimize the assembling of these parts within the carburetor body 10 to minimize the time required and the number of assembly operations necessary. The metering rod 66 is first preasserrrbled with its retainer 79. Spring 78 is dropped into bore 77 and then the assembled metering rod and retainer 70 is passed through the spring 78 into the emulsion tube 62 until the anged end of the `retainer 79 strikes the top of the spring 78. The lower end 68 of metering rod 66 extends through the passage 69 of the jet structure 56. The diaphragm S9 is a circular piece of synthetic rubber impervious to fuels, which are presently used in internal combustion engines. The circular diaphragm d is next placed within the bore 34 and the dimensions of the diaphragm 89 are such that its peripheral edge will fit snugly in bore 84 and will lay down onto the shoulder 8l. The diaphragm extends over the top of retainer 79. Next, the retainer 35 is placed with its flanged end downwardly against the center of the diaphragm 89. Spring 9@ is telescoped over the retainer 83, as shown in FIGURE 4. A gasket having an outside diameter substantially equal to that of the bore 84 is placed onto the periphery of the diaphragm 89. `Fitting d2 is placed into bore 84 so that spring 9d extends into the central bore 91 of the fitting to position the retainer 38 centrally of the assembly. The lower portion S3 of fitting 82 loosely fits within bore 84 while the upper portion 37 of fitting 82 is dimensioned to provide a press fit with bore S4. As the fitting 82 is pressed into the bore 84, the spring 99 is compressed so that it presses the retainer 8S onto diaphragm 80 and forces the diaphragm downwardly until the center `of the diaphragm makes contact with the anged top of the retainer 70. Further movement of fitting 88 into the bore 84- will compress spring 78 until the flanged end of retainer 7) aibuts the bottom of the cavity 86. This movement of the fit-ting 32 also presses spring 9@ downwardly, which forces retainer S8 against the diaphragm 89 and presses the diaphragm downwardly into the lower recess of the cavity v86. This action pulls the peripheral edge of diaphragm 89 down onto the shoulder Si and also provides a dished configuration of the diaphragm as shown specifically in FIGURES 3 and 4. As the fitting 32 is pressed completely to its lowest position, it forces the gasket 85 tightly against the peripheral edge of diaphragm titl and thus forms an air-tight seal between the diaphragm and the upper portion of cavity 86.

When the air motor is assembled in the manner described above and as shown in FIGURES 3 and 4, the diaphragm is automatically given the dished configuration shown The `configuration of diaphragm Sti provides a slack inwardly of its tightly held periphery so that as the center of diaphragm 8@ moves upwardly axially of the position of FIGURE 4, there is sufiicient slack or loop to provide ea-sy reciprocal motion up and down. Thus, the lassembly of the air motor parts, as described, automatically centers the retainers in their proper positions and also sets the diaphragm with the slack required for proper operation ofthe diaphragm. The assembly operation does not require skilled operators and little or no preassembling of parts prior to the final assembly of the air motor and metering rod; nor does the assembly procedure require any critical procedure for providing the slack required for diaphragm operation.

A passage 96 (FIGURE 2) is formed between the mixing conduit l2 from a region between the choke valve 26 and the throttle valve 22 to extend downwardly into the upper portion of `well 20. Within the passage 96 is pressfitted a restriction element 93 for controlling air fiow through passage 96 into the well 29. As shown in FIG- URE 4, well Ztl is also yconnected to the fuel in bowl 35 by a passage 97. Fuel flow through this passage is controlled by a jet 99 of predetermined size in the order of 0.030 inch.

Mounted within the cylindrical recess f6 formed in body casting itl is a pump piston Ml@ (FIGURE 2), which is connected to a pump piston rod 162. A spring 194 is fitted between the upper end of the pump cylinder 16 and the piston 199. The lower end of the pump cylinder 16 is closed by a fitting T196 having a central aperture 163 therethrough above which, biased by gravity, is a ball valve llt). A fuel passage M2 extends between the pump cylinder f6 and the cylindrical passage 1S formed in the body casting 10. Passage lf2 permits fuel flow into a fitting .114 closing `the lower end of cylindrical passage 18 and having at its upper end a valve seat in which the pointed end of a gravity Vbiased check valve 116 is fitted. The cylindrical passage 1S extends upwardly and intercepts the main fuel passage 5S, at which point a closure fitting 118 is fixed. Fitting 1113 forms an annular channel 117 with passage 58. Channel 11.7 is connected with a small aperture 119 through which fuel can be ejected from the cylindrical passage 13 into the main fuel passage 58 under pressure fr-om the pump piston 16%. Aperture 119 is formed off axis .relative to passage 53 so that the ejected fuel will not strike rod 66 and be directed into the well 2?.

The operation of the structures described are as follows: Fuel from the fuel bowl 36 fiows into both fthe pump cylinder 16 and the well structure Ztl, to ll these recesses to the level of the fuel in the bowl. Upon the turning over of the engine, air is sucked through the air filter 29 into the mixture conduit l2 and the intake manifold M. The flow of air through the booster ventur-i 32 provides a sub-atmospheric pressure within the venturi surface 34 which extends back through the fuel passage 58 to the upper end of fuel well Zti. The atmospheric pressure on the surface of the fuel within bowl 36, as is conventional and, as shown in Carlson et al., Patent No. 2,394,663, raises the fuel within the well 26 and simultaneously air is sucked through the restriction 9S and the bleed passage 96 into the upper portion of the fuel well. This air passes around and through the apertures 63 in the emulsion tube 62 to mix with the fuel an-d its vapor and to form an air-fuel emulsion. The emulsion is carried upwardly from the fuel well into the main fuel passage 555 and out the nozzle 60 to form a fuel and air mixture with the air passing through the mixture conduit 12. At high speeds, the flow of air through the apertures 63 in the emulsion tube 62 tends t-o remove all the fuel from between the well wall and tube 62 so that more 4apertures 63 are uncovered and an excessive amount of air passes into tube 62 to provide too lean a mixture. The provision of the fixed jet 99 and passage 97 from fuel bowl 36 allows the fuel level between the Well wall and tube 62 to be maintained with the provision of a sufficiently rich mixture.

At low speeds, the throttle 22 is partially closed so that the manifold vacuum in the intake manifold M below the throttle 22 is relatively high. This vacuum is effective Ithrough the passage 94 upon the upper surface of diaphragm 80 so `that the pressure of air in the main nozzle S8 against the under surface of diaphragm S0 will press the diaphragm upwardly an-d permit the metering rod and its retainer '7d to be carried with it in an upward direction. At low speeds the air in the mixture conduit 12, upstream of the throttle is at a greater pressure than the pressure of air in the intake manifold downstream of the throttle. This upstream pressure is effective upon the diaphragm Sti through nozzle passage 5-8 and bore 77. This brings the thicker portion of the metering rod end 6d into the main jet orifice 69 to cut down the flow of fuel through this orifice in accordance with the lower engine speed. As the throttle 22 is opened progressively from low speed to high speed, the vacuum pressure in the manifold drops and permits. spring 9d to bias the diaphragm it@ and the metering rod 66 downwardly until a thinner portion of the rod end 6ft enters the jet orifice to provide a greater flow of fuel into the mixing conduit 12.

The accelerating pump rod 162 is connected with `a lost motion connection 124 (FIGURES l and 2) by a linkage 126 to the throttle lever 128 which is fixed for simultaneous movement with the throttle shaft 24. Throttle lever 128 has an arm 129 adapted to be connected to any means for manual operation of the throttle 22. Any opening of the throttle by lever 128 will allow spring 10d through the lost motion connection 124 to press accelerating pump piston Miti downwardly and force fuel out of the lower portion of the pump cylinder 16 through passage 112 upwardly past the gravity biased valve 116 Iand into the annular portion 117 of the fitting 118. This accelerating fuel under pressure will spurt out of the pass-age 119 .and will be directed into the nozzle structure 69 to provide additional fuel for the increased air flow due to the opening of the throttle 22. This provides rapid response of the engine upon opening of the throttle.

A low speed or idle circuit is provided in the carburetor and is not shown in this application as it does not constitute a part of the invention. However, it may be si-rnilar to that described and disclosed in the copending application of Ralph E. Kalert, lr., and lesse L. Szwargulski, Serial No. 146,896 filed October 23, 1961.

The choke valve 26 is controlled during cold weather and during c-old start-s by a thermostatic choke control device enclosed in a housing structure 13u. The choke control consists of a thermostatic coiled `bil-metallic spring 132 having one end fixed to a stationary stud 134- mounted on the housing 130. The other end of the thermostatic spring rests against one arm 136 of a lever fixed to the choke shaft 28. When the engine is cold, the thermostatic spring is tensioned in one direction to press against the end of the lever 136 and rotate the choke valve 26 toward a closed position. The fiow of air through the mixing conduit 12 at this point will partially open the unbalanced choke valve. 26 to permit sutilcient air to pass on into the intake manifold M. As the engine heats up, the spring 132 relaxes and releases the end of lever 136 so that after .a predetermined temperature has been reached the thermostatic coil 132 has no effect on the cho-ke 26, which now will remain open by gravity, due to its unbalanced construction. The details of the choke are shown and described in the copending application of Jesse L. Szwargulski, Serial No. 146,371, filed September 25, 1963 now Patent No. 3,133,977.

The combination of the metering pin 66 and its supporting structure enables a rapid removal and replacement of the metering rod by loosening screws 37. The only requirements necessary are the removal of bowl 36 to expose the lower end 68 of rod 66. Any appropriate tool may be used to pull the rod 66 downwardly through the orifice 56. Because of the flexible nature of the rib portions 74 of the retainer 76, they will release and liex out of the groove 76. A new rod can be replaced by inserting it upwardly through the jet orifice 56 until its upper end contacts the resilient rib portions 7d of retainer 7&1. These 4will again fiex over the rod end and permit the end of the rod to enter the retainer 76 and `'allow peripheral ribs 7d to snap into the groove 76 of the rod to lock itin position. This novel arrangement of metering rod support permits rapid removal of the metering rod for replacement with other rods having a different formed end structure 68 to compensate for different operating conditions of the engine.

I claim:

1. lA carburetor for an internal combustion engine, said carburetor comprising a body formed with an air and fuel mixture conduit adapted to be connected to the intake manifold of said engine and a fuel bowl, said body including a vertical fuel passage extending between said fuel bowl and said mixture conduit, a throttle movably mounted within said mixture conduit, said fuel passage including a well having a predetermined restriction at the lower end thereof, said body formed with a cavity above said vertical fuel passage and an opening between said cavity and the top of said vertical fuel passage, an emulsion tube fixed vertically within said vertical passage, means supplying air to said emulsion tube, a metering rod extending through said emulsion tube and having one end thereof shaped with varying thickness. and positioned within and for movement through said fuel passage restriction, a retainer in said opening supporting said metering rod in said well port-ion, a diaphragm extending across said cavity, a first spring within said cavity on said one side of said diaphragm and biasing said diaphragm toward said restriction and providing a dished conguration of said diaphragm, means sealing the peripheral edge of Said diaphragm to the cavity wall with the diaphragm in said dished configuration, a duct in said tbody extending from said cavity on said one side of said diaphragm to said mixture conduit downstream of said throttle to connect said diaphragm to low air pressures within said engine intake manifold whereby said diaphragm may be moved against said first spring in a direction opposite to said one direction, and a second spring between said body and said retainer holding said retainer against the other side of said diaphragm whereby said metering rod is caused to follow the movements of said diaphragm.

2. A carburetor as defined in claim 1, said second spring eing weaker than said first spring whereby said diaphragm is normally biased in said one direction.

`3. A carburetor as defined in claim i, a second retainer interposed between said first spring and said diaphragm.

References @ited by the Examiner UNlTED STATES PATEN'S 1,659,263 2/28 Harris 92-95 2,268,543 1/42 Coberly 29-1564 2,394,663 2/46 Carlson et al 26h-69 X 2,478,8l8 8/49 Geiger et al 29-l56-4 2,873,956 2/59 Zubaty 261-69 2,882,027 4/59 Cook et al. 261-69 2,969,965 l/61 Braun 261-69 X 3,025,877 3/62 Buckay 251-61 X 3,084,865 4/63 Fleer et al 251-122 X 3,136,827 6/64 Szwargulslci 261-60 HARRY B. THORNTON, Primary Examiner.

RONALD R. WEAVER, Examiner. 

1. A CARBURETOR FOR AN INTERNAL COMBUSTION ENGINE, SAID CARBURETOR COMPRISING A BODY FORMED WITH AN AIR AND FUEL MIXTURE CONDUIT ADAPTED TO BE CONNECTED TO THE INTAKE MANIFOLD OF SAID ENGINE AND A FUEL BOWL, SAID BODY INCLUDING A VERTICAL FUEL PASSAGE EXTENDING BETWEEN SAID FUEL BOWL AND SAID MIXTURE CONDUIT, A THROTTLE MOVABLY MOUNTED WITHIN SAID MIXTURE CONDUIT, SAID FUEL PASSAGE INCLUDING A WELL HAVING A PREDETERMINED RESTRICTION AT THE LOWER END THEREOF, SAID BODY FORMED WITH A CAVITY ABOVE SAID VERITCAL FUEL PASSAGE AND AN OPENING BETWEEN SAID CAVITY AND THE TOP OF SAID VERTICAL FUEL PASSAGE, AN EMULSION TUBE FIXED VERTICALLY WITHIN SAID VERTICAL PASSAGE, MEANS SUPPLYING AIR TO SAID EMULSION TUBE, A METERING ROD EXTENDING THROUGH SAID EMULSION TUBE AND HAVING ONE END THEREOF SHAPED WITH VARYING THICKNESS AND POSITIONED WITHIN AND FOR MOVEMENT THROUGH SAID FUEL PASAGE RESTRICTION, A RETAINER IN SAID OPENING SUPPORTING SAID METERING ROD IN SAID WELL PORTION, A DIAPHRAGM EXTENDING ACROSS SAID CAVITY, A FIRST SPRING WITHIN SAID CAVITY ON SAID ONE SIDE OF SAID DIAPHRAGM AND BIASING SAID DIAPHRAGM TOWARD SAID RESTRICTION AND PROVIDING A DISHED CONFIGURATION OF SAID DIAPHRAGM, MEANS SEALING THE PERIPHERAL EDGE OF SAID DIAPHRAGM TO THE CAVITY WALL WITH THE DIAPHRAGM IN SAID DISHES CONFIGURATION, A DUCT IN SAID BODY EXTENDING FROM SAID CAVITY ON SAID ONE SIDE OF SAID DIAPHRAGM TO SAID MIXTURE CONDUIT DOWNSTREAM OF SAID THROTTLE TO CONNECT SAID DIAPHRAGM TO LOW AIR PRESSURES WITHIN SAID ENGINE INTAKE MANIFOLD WHEREBY SAID DIAPHRAGM MAY BE MOVED AGAINST SAID FIRST SPRING IN A DIRECTION OPPOSITE TO SAID ONE DIRECTION, AND A SECOND SPRING BETWEEN SAID BODY AND SAID RETAINER HOLDING SAID RETAINER AGAINST THE OTHER SIDE OF SAID DIAPHRAGM WHEREBY SAID METERING ROD IS CAUSED TO FOLLOW THE MOVEMENT OF SAID DIAPHRAGM. 